Conventionally, various composite materials made of a carbonaceous material such as carbon particles or carbon nano-tubes and a resin have been proposed. Improvement of strength and the like can be attained by forming a composite of a resin with these carbonaceous materials. Graphite is a hexagonal layered compound of SP2 carbons, and one layer constituting graphite is referred to as graphene. Conventionally, in order to obtain graphene, a method for treating silicon carbide with heating and a method for laminating graphene onto a metal film such as copper foil by a CVD method have been known.
On the other hand, a method has been known in which oxidized graphene and exfoliated graphite that have less number of stacked graphene layers than the original graphite are obtained by treating graphite with strong acid, doping ions into interlayer of the graphite, and treating with rapid heating (Patent Document 1 described below).
In addition, conventionally, various composite materials made of exfoliated graphite obtained by delaminating graphite and a polymer have been studied. For example, Non-Patent Document 1 described below has reported that styrene polymer chains are grafted onto the surface of graphene when a polymerization initiator and a styrene monomer component are mixed in the presence of exfoliated graphite obtained by delaminating graphite by chemical treatment and the monomer is polymerized.